[Elecraft] Digital Mode Interface for the KX3 for WSJT modes

[Jim Brown]

On 7/15/2012 12:15 AM, Edward R. Cole wrote:
> I rarely listen to the audio of digital signals since my brain cannot
> decode them, anyway.  With a 3.5mm phone plug inserted the internal
> speaker is disconnected so I suppose you are using either headphones
> or ext. speaker.  No need to hear the signal so volume on KX3 is
> adequate to set proper level for digital sw.

I operate RTTY, JT65, FSK441, and ISCAT fairly often, and I've just 
started with PSK2K. I find it VERY useful, even IMPORTANT to listen to 
what the decoder is seeing. I get close to "right" tuning on RTTY by 
ear, then tweak it with the display.  When using FSK441 to work meteor 
scatter I'll hear a ping and know to be looking for it. Likewise with 
JT65 and ISCAT I'll be able to hear most of the signals that can be 
decoded, as well as noise and QRM.  And when using some of these modes 
on a band with little activity (like 6M, or 160M during the summer) I'll 
be CQing beacon-style while doing something around the shack. Hearing a 
signal pulls me back to the operating desk.

There are at least a half dozen other digital modes in use, and with 
some you almost need to hear them to recognize which decoding program to 
use. :)

>Audio interface should use isolation transformers, and the mic audio
>requires a pot for setting proper modulation level

Both statements are absolutely untrue. I've shown how proper 
chassis-to-chassis bonding prevents hum and buzz from power-related 
leakage currents, and it is trivially easy to set audio level using a 
combination of the output controls on the computer sound card and the 
mic gain on the radio.

73, Jim K9YC